<template>
  <div id="cesiumContainer"></div>
</template>
<script setup>
/**
 * 本案例是展示 Entity.availability 时间相关的属性
 */
import * as Cesium from "cesium";
import TOKEN from "@/utils/cesium/token.js";
onMounted(async () => {
  Cesium.Ion.defaultAccessToken = TOKEN;
  // 实例化
  const viewer = new Cesium.Viewer("cesiumContainer", {
    // 界面控件 全部关闭
    animation: false, // 左下角的动画控制器组件
    baseLayerPicker: false, // 底图组件，选择三维数字地球的底图（imagery and terrain）。
    fullscreenButton: true, // 全屏组件
    vrButton: true, // VR模式
    geocoder: false, // 地理编码（搜索）组件
    homeButton: false, // 首页，点击之后将视图跳转到默认视角
    infoBox: false, // 信息框
    sceneModePicker: false, // 场景模式，切换2D、3D 和 Columbus View (CV) 模式。
    selectionIndicator: false, //是否显示选取指示器组件
    timeline: false, // 时间轴
    navigationHelpButton: false, // 帮助提示，如何操作数字地球。
    // 如果最初应该看到导航说明，则为true；如果直到用户明确单击该按钮，则该提示不显示，否则为false。
    navigationInstructionsInitiallyVisible: false,
  });
  // 加载地形数据
  const terrainProvider = await Cesium.CesiumTerrainProvider.fromIonAssetId(1);
  viewer.terrainProvider = terrainProvider;
  // 隐藏logo
  viewer._cesiumWidget._creditContainer.style.display = "none";

  // Click the VR button in the bottom right of the screen to switch to VR mode.

  viewer.scene.globe.enableLighting = true;
  viewer.scene.globe.depthTestAgainstTerrain = true;

  // Follow the path of a plane. See the interpolation Sandcastle example.
  Cesium.Math.setRandomNumberSeed(3);

  var start = Cesium.JulianDate.fromDate(new Date(2015, 2, 25, 16));
  var stop = Cesium.JulianDate.addSeconds(start, 360, new Cesium.JulianDate());

  viewer.clock.startTime = start.clone();
  viewer.clock.stopTime = stop.clone();
  viewer.clock.currentTime = start.clone();
  viewer.clock.clockRange = Cesium.ClockRange.LOOP_STOP;
  viewer.clock.multiplier = 1.0;
  viewer.clock.shouldAnimate = true;

  function computeCirclularFlight(lon, lat, radius) {
    var property = new Cesium.SampledPositionProperty();
    var startAngle = Cesium.Math.nextRandomNumber() * 360.0;
    var endAngle = startAngle + 360.0;

    var increment = (Cesium.Math.nextRandomNumber() * 2.0 - 1.0) * 10.0 + 45.0;
    for (var i = startAngle; i < endAngle; i += increment) {
      var radians = Cesium.Math.toRadians(i);
      var timeIncrement = i - startAngle;
      var time = Cesium.JulianDate.addSeconds(
        start,
        timeIncrement,
        new Cesium.JulianDate()
      );
      var position = Cesium.Cartesian3.fromDegrees(
        lon + radius * 1.5 * Math.cos(radians),
        lat + radius * Math.sin(radians),
        Cesium.Math.nextRandomNumber() * 500 + 1800
      );
      property.addSample(time, position);
    }
    return property;
  }

  var longitude = -112.110693;
  var latitude = 36.0994841;
  var radius = 0.03;

  var modelURI = "/cesiumData/models/CesiumBalloon/CesiumBalloon.glb";
  var entity = viewer.entities.add({
    availability: new Cesium.TimeIntervalCollection([
      new Cesium.TimeInterval({
        start: start,
        stop: stop,
      }),
    ]),
    position: computeCirclularFlight(longitude, latitude, radius),
    model: {
      uri: modelURI,
      minimumPixelSize: 64,
    },
  });

  entity.position.setInterpolationOptions({
    interpolationDegree: 2,
    interpolationAlgorithm: Cesium.HermitePolynomialApproximation,
  });

  // Set initial camera position and orientation to be when in the model's reference frame.
  var camera = viewer.camera;
  camera.position = new Cesium.Cartesian3(0.25, 0.0, 0.0);
  camera.direction = new Cesium.Cartesian3(1.0, 0.0, 0.0);
  camera.up = new Cesium.Cartesian3(0.0, 0.0, 1.0);
  camera.right = new Cesium.Cartesian3(0.0, -1.0, 0.0);

  viewer.scene.postUpdate.addEventListener(function (scene, time) {
    var position = entity.position.getValue(time);
    if (!Cesium.defined(position)) {
      return;
    }

    var transform;
    if (!Cesium.defined(entity.orientation)) {
      transform = Cesium.Transforms.eastNorthUpToFixedFrame(position);
    } else {
      var orientation = entity.orientation.getValue(time);
      if (!Cesium.defined(orientation)) {
        return;
      }

      transform = Cesium.Matrix4.fromRotationTranslation(
        Cesium.Matrix3.fromQuaternion(orientation),
        position
      );
    }

    // Save camera state
    var offset = Cesium.Cartesian3.clone(camera.position);
    var direction = Cesium.Cartesian3.clone(camera.direction);
    var up = Cesium.Cartesian3.clone(camera.up);

    // Set camera to be in model's reference frame.
    camera.lookAtTransform(transform);

    // Reset the camera state to the saved state so it appears fixed in the model's frame.
    Cesium.Cartesian3.clone(offset, camera.position);
    Cesium.Cartesian3.clone(direction, camera.direction);
    Cesium.Cartesian3.clone(up, camera.up);
    Cesium.Cartesian3.cross(direction, up, camera.right);
  });

  // Add a few more balloons flying with the one the viewer is in.
  var numBalloons = 12;
  for (var i = 0; i < numBalloons; ++i) {
    var balloonRadius =
      (Cesium.Math.nextRandomNumber() * 2.0 - 1.0) * 0.01 + radius;
    var balloon = viewer.entities.add({
      availability: new Cesium.TimeIntervalCollection([
        new Cesium.TimeInterval({
          start: start,
          stop: stop,
        }),
      ]),
      position: computeCirclularFlight(longitude, latitude, balloonRadius),
      model: {
        uri: modelURI,
        minimumPixelSize: 64,
      },
    });

    balloon.position.setInterpolationOptions({
      interpolationDegree: 2,
      interpolationAlgorithm: Cesium.HermitePolynomialApproximation,
    });
  }
});
</script>

<style scoped>
#cesiumContainer {
  width: 100%;
  height: 100%;
}
</style>
